The invention disclosed herein relates generally to performing storage operations on electronic data in a computer network. More particularly, the present invention relates to migrating resources used in performing storage operations from one storage operation cell to another.
Storage management systems have evolved over time into complex entities with many components including hardware and software modules designed to perform a variety of different storage operations on electronic data. Current storage management systems employ a number of different methods to perform storage operations on electronic data. For example, data can be stored in primary storage as a primary copy or in secondary storage as various types of secondary copies including, as a backup copy, a snapshot copy, a hierarchical storage management copy (“HSM”), as an archive copy, and as other types of copies.
A primary copy of data is generally a production copy or other “live” version of the data which is used by a software application and is typically in the native format of that application. Primary copy data may be maintained in a local memory or other high-speed storage device that allows for relatively fast data access. Such primary copy data is typically retained for a period of time (e.g., a number of seconds, minutes, hours or days) before some or all of the data is stored as one or more secondary copies, for example, to prevent loss of data in the event a problem occurs with the data stored in primary storage.
Secondary copies may include point-in-time data and may be intended for long-term retention (e.g., weeks, months or years depending on retention criteria, for example as specified in a storage policy as further described herein) before some or all of the data is moved to other storage or discarded. Secondary copies may be indexed so users can browse and restore the data at another point in time. After certain primary copy data is copied to secondary storage, a pointer or other location indicia such as a stub may be placed in the primary copy to indicate the current location of that data.
One type of secondary copy is a backup copy. A backup copy is generally a point-in-time copy of the primary copy data stored in a backup format as opposed to in native application format. For example, a backup copy may be stored in a backup format that is optimized for compression and efficient long-term storage. Backup copies generally have relatively long retention periods and may be stored on media with slower retrieval times than other types of secondary copies and media. In some cases, backup copies may be stored at an offsite location.
Another form of secondary copy is a snapshot copy. From an end-user viewpoint, a snapshot may be thought of as a representation or image of the primary copy data at a given point in time. A snapshot generally creates a bit map or block level representation of a primary copy volume at a particular moment in time. Users typically gain a read-only access to the record of files and directories of the snapshot. By electing to restore primary copy data from a snapshot taken at a given point in time, users may also return the current file system to the prior state of the file system that existed when the snapshot was taken.
A snapshot may be created instantly, using a minimum of file space, but may still function as a conventional file system backup. A snapshot may not actually create another physical copy of all the data, but may simply create pointers that are mapped to specific blocks of data taken at the point in time of the snapshot.
In some conventional systems, once a snapshot has been taken, the original blocks in use at the time at snapshot are preserved in a cache such that only subsequent changes to the file system would overwrite them. Therefore, the initial snapshot may use only a small amount of disk space needed to record a mapping or other data structure representing or otherwise tracking the blocks that correspond to the current state of the volume (e.g., a bit map). Additional disk space is usually only required when files are actually modified later.
Furthermore, when files are modified, typically only the pointers which map to blocks are copied, not the blocks themselves. In some systems, for example in the case of copy-on-write snapshots, when a block changes in primary storage, the block is copied to secondary storage before the block is overwritten in primary storage and the snapshot mapping of file system data is updated to reflect the changed block(s) at that particular point in time.
A Hierarchical Storage Management (“HSM”) copy is generally a copy of the primary copy data, but typically includes only a subset of the primary copy data that meets a certain criteria and is usually stored in a format other than the native application format. For example, an HSM copy might include only that data from the primary copy that is larger than a given size threshold or older than a given age threshold and that is stored in a backup format. Often, HSM data is removed from the primary copy, and a stub is stored in the primary copy to indicate its new location. When a user subsequently requests access to the HSM data that has been removed or migrated, systems then use the stub to locate the data and often make recovery of the data appear transparent, even though the HSM data may be stored at a location different from the remaining primary copy data.
An archive copy is generally similar to an HSM copy, however, the data satisfying criteria for removal from the primary copy is generally completely removed with no stub left in the primary copy to indicate the new location (i.e., where it has been moved to). Archive copies of data are generally stored in a backup format or other non-native application format. In addition, archive copies are generally retained for very long periods of time (e.g., years) and in some cases are never deleted. Such archive copies may be made and kept for extended periods in order to meet compliance regulations or for other permanent storage applications.
In some systems, data may be moved over its lifetime moves from expensive quick access storage, to less expensive slower access storage. This process of moving data through these various tiers of storage is sometimes referred to as information lifecycle management (“ILM”). This is the process by which data is “aged” from more expensive forms of secondary storage with faster access/restore times down through less expensive secondary storage with slower access/restore times, for example, as the data becomes less important or mission critical over time.
Examples of various types of data and copies of data are further described in the above-referenced related applications that are hereby incorporated by reference in their entirety. One example of a system that performs storage operations on electronic data that produce such copies is the QINETIX storage management system by COMMVAULT Systems of Oceanport, N.J.
The QINETIX system provides a modular storage management architecture that may include, among other things, storage manager components, client or data agent components, and media agent components as further described in U.S. patent application Ser. No. 10/818,749 which is hereby incorporated herein by reference in its entirety.
The QINETIX system also provides for hierarchically configuring storage operation cells to perform certain other types of storage operations including snapshot copies, HSM copies, archive copies, and certain other types of copies of electronic data, as further described in U.S. patent application Ser. No. 11/120,619 which is hereby incorporated by reference in its entirety.
The QINETIX system, as further disclosed in U.S. patent application Ser. No. 11/120,619, also provides for meaningful integration between and among HSM systems and Storage Resource Management (“SRM”) systems. SRM systems are typically concerned with monitoring the health, status, and other information associated with primary copies of data (e.g., live or production line copies). For example, an SRM application may monitor the capacity of a volume storing a primary copy of data, and the rate of data transfer relative to the available storage of that volume. In contrast, HSM systems are typically concerned with data transport to secondary storage, such as the parameters and particulars associated with the storage and migration of secondary copy data as opposed to monitoring of information associated with primary copy data. HSM systems are thus generally directed to secondary copies and other archival data volumes. For example, an HSM system may be directed to migrating or otherwise transferring data to a secondary copy.
Transferring data to any one of the aforementioned secondary copy types may be performed using a storage management system, using one or more copy devices, components or other data transfer resources. Depending on storage requirements, secondary copy operations or other storage operations may be performed at various times which may result in an undesirably high number of storage operations being performed at a particular time using the same or similar resources. Meanwhile, other secondary copy resources may be underutilized.
In some instances, it may be desirable to migrate or reassign storage resources from one storage operation system, or subset of a system, such as a cell, to another to provide additional routing options or to help alleviate any bottlenecks or congestion that may occur based on established commitments or system configuration.
There are also situations where storage resources may be physically moved, and certain storage management components should be migrated to new places in the system to continue to support the moved storage resources.
Moreover, in certain situations, component migration, reallocation or movement, may be desired or necessary, such as in a disaster recovery (DR) situation where data and/or resources are temporarily or permanently moved to another storage operation cell.